1. Field of the Invention
This invention relates generally to medical devices that are implantable in the human body and more particularly relates to a subcutaneously implantable direct delivery access port capable of delivering filtered drugs to the ventricles of the brain or to the intraspinal area and, from the same device, allowing the removal of unfiltered cerebrospinal fluid from the brain or spinal area
2. Description of Related Art
It is often desirable for a physician or other health care professional to withdraw cerebrospinal fluid (CSF) from a patient in order to assess the condition of the CSF or to administer drug to the CSF. Access ports, such as the model 8506 ICV Access Port and the 8507 Intraspinal Port, developed by Medtronic, Inc. of Minneapolis, Minn., allow the physician or other healthcare professional to intermittently withdraw CSF from the ventricles of a patient's brain or intraspinal space or administer drug to the CSF.
These access ports are typically placed cranially or over the ribs and are connected to a catheter which is surgically placed in the intraventricular space of the brain or intraspinal area of the spinal cord. Physicians often require the ability to take CSF samples through the port to confirm port and catheter patency prior to injecting drugs or for evaluation purposes. CSF is withdrawn by inserting a needle through the patient's skin and through a septum that forms the top of the port. The end of the needle is located in the port and CSF is withdrawn from the patient through the catheter and port.
When it is desirable to administer drug to the CSF, a needle is inserted through the patient's skin, through the septum and into the port which is connected to a catheter. The drug is passed into the port where it passes through the catheter into the patient's CSF.
These and other similar products may represent an infection risk to the patient because the drugs are introduced across the blood brain barrier to the neuraxis without first passing through a bioretentive filter in the port. If a filter is placed across the fluid path, it is believed that taking repeated CSF samples through the filter will cause the filter to clog. As the filter becomes clogged, it becomes more difficult if not impossible to either take further CSF samples or administer drugs to the patient through the port. This is a problem in need of a solution.